August 6, 2008—The dry Martian surface may show signs of ancient aquatic activity in this June 28 HiRISE image from the Mars Reconnaissance Orbiter.

The visible valley is associated with a long pit, Ophir Cavus, which also spawned a nearby valley system. This topography suggests that the pit's birth, perhaps by an ice-melting volcanic eruption, produced a substantial water flow.

The light-toned areas seen on the plains may be minerals that were deposited by flowing water.